Currently, a wide range of portable consumer electronics that are not dedicated to audio playback provide increasingly important audio capabilities. These portable consumer electronics may include, for example, smart phones, laptops, notebooks, tablet computers, and personal digital media players. These portable consumer electronics are often constrained in both x-y area and z-height or thickness such that the speaker driver included therein must be designed to meet the sizing constraints while providing adequate sound quality.
Typically, a speaker driver in a portable consumer electronic such as a smart phone includes a coil and a magnet unit that are completely enclosed in a plastic housing referred to as a speaker box, except of course for the acoustic output port. One disadvantage of this configuration is that the coil generates heat when audio is being played and the plastic housing traps the generated heat in the speaker driver. If the magnet unit exceeds a given temperature, the magnet unit may become demagnetized and this will result in terminal damage to the speaker driver. In order to address this problem, the magnet units in conventional speaker drivers are required to make use of high temperature grade magnets. However, high temperature grade magnets are unable to store as much flux density as the lower temperature grade magnets, leaving the conventional speaker that uses such a high temperature magnet lacking in sensitivity.